Pressure-gage



R. McK. NELSON.

PRESSURE GAGE.

APPLICATION FILED SEPT. 20,4920.

1,391, 1 38. PtentedSept. 20, 1921.

. HIVENTQR ATTORNEYS uNirED STATES infirlxlr OFFICE.

MOKINLEY NELSON, OF SELLERSVILLE, PENNSYLVANIA, ASSIGNOR T0 or PENNSYLVANIA To fall whom 't-may concern.

Be it known that I, RALPH MGK. NELSON, a citizen of fthe .United States, residing at Sellersville, in the .county of Bucks and State of Pennsylvania, have invented certain new and useful Improvements in. Pressure-Gages, Lof which the followingis a full, clear, .ande-Xact description.

The yinvention which forms the subject of this application for Letters Patent 1s 'an improvement in pressure gages, the nature and purpose of Lwhich will be .readily understood from the following considerations.

Certain regulations, State or munlcipal, require that all boilers of a certain type be equipped with pressure gages, and furthermore that such gages must be constructed and adapted to indicate any pressure up to a prescribed maximum. The boiler may be one for domestic heating and not designed and never intended to generate more than a few pounds of steam, say ten at most. Nevertheless, it is required that `the gage shall be capable of indicating much higher pressure, say thirty pounds, and this 1s an onerous requirement` as it necessitates the construction and use of a high grade instrument, the cost of which is quite out of proportion to that of the boiler.

Manufacturers of such boilers have therefore been required to resort to various expedients to meet this regulation and for such purpose have usually devised and made dupleX- gages, comprising in a single instrument two dials and two pointers, each of the latter being operated by its own Bourdon tube or equivalent device, one of which isadapted for indicating low pressure and the other pressure over a much greater range. These instruments while useful and desirable are still objectionable on thescore of cost, and I have therefore Sought to produce a simpler and cheaper device which will accomplish the desired result.

.According to my present improvement I combine in thel same instrument two dials or scales and two pointers. One of these latter, or that intended for indicating the lower pressures is operated by a Bourdon tube of the usual character which is rigidly mounted on a Xed standard in the casing at a point intermediate its two ends. The point of support, however, is much nearer one end than the other and the longer end is ronnected with the usual means for ro- '.pressures than the other.

.intermediate .mechanism for UmrEnsTA'rEs GAUGE COMPANY, or NEW Yonx, N. Y., A .CORPORATION PRESSURE-GAGE.

` Specification of Letters Patent. 'Patented Spt, 20, 1921 Application'led September 20, 1920. Serial No. 411,429.

tating'the pointerwto an amount proportional to the distortion of the tube .under internal pressure.

-Tfhe other or shorter endet" the `tube is similarly connected with means of the same character for imparting movement to a smaller pointer `moving over a smaller scale and capable of registering much higher The invention involves, therefore, the combination with one and the sa-me tube of two pointers and moving the pointers properlyl constructed as to the character of the gears and other parts used to enable one to register low pressures and the other pressures of a much more extended range. 1

This improvement is shown in the accompanying drawing, in which- Figure 1 is a face view of the outside of the gage casing; and

Fig. 2 is a view in elevation of the interior mechanisms for moving the pointers.

The instrument is of the usual pattern and has a dial plate 1, on which are marked two scales, the outer and larger scale 2 hav 1ng,say ten divisions, the inner and smaller scale 3 having, say thirty divisions. Each scale has a pointer 4 or 5.

- In the interior of the casing is a fixed stud or standard 6, and to this is rigidly secured an ordinary gage tube or spring 7 the point of union being at about a third or less of the length of the entire tube. The longer free end is connected by a link 8 to a segmental rack 9 pivoted at 10V and engaging with a pinion 11 on the shaft of the pointer 4. The shorter end is similarly connected by a link 12 with a' segmental rack 13 which engages with a pinion 14 on the shaft of pointer 5.

.Manifestly, since the movement for a given pressure of the longer end is much greater than that of the shorter end, the sizes of the racks and the nature of the intermediate gearing will be correspondin ly differentthat is to say, the racks are of gifferen-t radius and adapted to produce the proper movements of the pointers for a given movement of the tube, the pinions meshing with said racks being of di'erent diameters. When the longer arm has indicated ten pounds pressure the rack bar encounters a fixed sto 15 and the pointer can move no farther. he other pointer, however, will indicate by the same relative movement in all thirty pounds, which ordinarily is beyond the capacity of the boiler.

This is an extremely simple instrument which may be produced at a greatly reduced cost, but which meets all the requirements of the more expensive and complicated devices heretofore designed and built for the same purpose.

What I claim is:

l. In a pressure gage, the combination with the same dial having two Vscales thereon and pointers for said scales, of a pressure tube rigidly mounted at a point intermediate its ends and nearer one end than the other, of means operated by the tWo free -With the same dial or plate having a loW pressure scale and a higher pressure scale thereon, and tWo pointers movable over the same, of a pressure tube rigidly mounted on a fixed support at a'pointnearer .one y, end

than the other, racks of different dimensions and pinions of different diameters connected respectively with the longer andthe shorter ends of the said tube and geared With'the shafts which carry the tWo pointers. V

signature.

40 In testimony whereof I hereto aiix my 

